A vehicle control system that sequentially determines target traveling positions based on the actual traveling position of a master work vehicle and navigates a slave work vehicle toward the target traveling positions is known from Patent Document 1. In this vehicle control system, control modes are disclosed, such as one in which the slave work vehicle is controlled to follow the master work vehicle so as to maintain offset amounts in X (longitude) and Y (latitude) directions set for the master work vehicle, and one in which the slave work vehicle is controlled to follow the master work vehicle, using a traveling route that is obtained by translating a traveling track of the master work vehicle by the work width as a target traveling route.
The following control of Patent Document 1 is intended for work performed on work ground with a large area, rather than ground work performed on work ground such as a field with a relatively small area that is bounded by a ridge or the like. The ground work on such work ground (agricultural fields), namely, ground work for agricultural purposes is performed using back and forth traveling in which the vehicles travel while repeatedly performing straight work traveling and U-turns in the central area of the work ground, and loop traveling in which the vehicles perform work while traveling in a loop in a loop work area, which is defined as the perimeter of the U-turn work area. Accordingly, the work ground is divided in advance into the U-turn work area and the loop work area. The central work traveling, which corresponds to work traveling in the U-turn work area, and the loop traveling, which corresponds to work traveling in the loop work area, use different algorithms for redirection and navigation.
It is known from, for example, Patent Document 2 that a single unmanned work vehicle performs ground work such as cultivation work with respect to the U-turn work area and the loop work area. However, it is impossible to realize ground work constituted by the central work traveling and the loop traveling with the work vehicle cooperation control in which a slave work vehicle follows a master work vehicle, only by combining the control disclosed in Patent Documents 1 and 2.